The present invention relates to methods, systems and apparatus for use in wireless (mobile) telecommunications systems, and in particular to paging procedures in such systems.
Third and fourth generation mobile telecommunication systems, such as those based on the 3GPP defined UMTS and Long Term Evolution (LTE) architectures, are able to support more sophisticated services than simple voice and messaging services offered by previous generations of mobile telecommunication systems.
For example, with the improved radio interface and enhanced data rates provided by LTE systems, a user is able to enjoy high data rate applications such as mobile video streaming and mobile video conferencing that would previously only have been available via a fixed line data connection. The demand to deploy third and fourth generation networks is therefore strong and the coverage areas for these networks is expected to increase rapidly.
The anticipated widespread deployment of third and fourth generation networks has led to the parallel development of devices and applications which, rather than taking advantage of the high data rates available, instead take advantage of the robust radio interface and increasing ubiquity of the coverage area. Examples include so-called machine type communication (MTC) applications, which are typified by semi-autonomous or autonomous wireless communication devices (i.e. MTC devices) communicating small amounts of data on a relatively infrequent basis. Examples include so-called smart meters which, for example, might be located in a customer's house and periodically transmit information back to a central MTC server relating to the customer's consumption of a utility, such as gas, water, electricity and so on. Further information on characteristics of MTC-type devices can be found, for example, in the corresponding standards, such as ETSI TS 122 368 V10.530 (2011 July)/3GPP TS 22.368 version 10.5.0 Release 10) [1]. Some typical characteristics of MTC type terminal devices/MTC type data might include, for example, characteristics such as low mobility, high delay tolerance, small data transmissions, a level of predictability for traffic usage and timing (i.e. traffic profile), relatively infrequent transmissions and group-based features, policing and addressing.
As a result of the increasing use of wireless telecommunications networks there is a desire to ensure networks can support a corresponding increase in traffic. One particular area where capacity issues may arise is for paging procedures. As well as being of a concern generally, the paging capacity of networks could potentially become one of the key considerations for providing widespread support for MTC devices. This is because MTC devices can be expected to be introduced into networks in much larger numbers than conventional terminal devices, perhaps by an order of magnitude or more. Furthermore, in addition to the expected large number of MTC devices, the nature of machine-to-machine/MTC-type traffic means the ratio of idle devices to active devices can be expected to be relatively high among MTC devices. Consequently, it may be expected the majority of MTC terminal device in a network will be in an idle state with the network reliant on paging to initiate communications with the device. Furthermore still, for power saving purposes it can be expected that many MTC devices will use discontinuous transmission and reception techniques in communicating with the network. The consequent reduction in the number of available paging occasions for such devices adds further to the likelihood of paging capacity becoming a bottleneck in wireless telecommunications systems.
There is therefore a desire for methods and apparatus which support paging procedures that can help reduce the potential for paging congestion in wireless telecommunications systems.